The present invention relates generally to mammalian cytokines, and particularly to cloning and expression of a biologically active recombinant bovine GM-CSF capable of inducing hematopoietic cell development.
Granulocyte-macrophage colony stimulating factor (GM-CSF) refers to a protein capable of inducing development of granulocyte and macrophage precursor cells from bone marrow progenitors. GM-CSF also appears to regulate the activity of mature, differentiated granulocytes and macrophages. Murine GM-CSF was initially identified as a 23 kilodalton protein present in preparations obtained from endotoxin-conditioned mouse lung which stimulated development of granulocyte and macrophage precursor colonies in soft agar cultures. See Burgess et al., J. Biol. Chem. 252:1998 (1977). Human GM-CSF activity was partially purified from placental conditioned medium by Nicola et al., Blood 54:614 (1979). Human GM-CSF has also been identified in cultures of the human T-lymphoblast cell line Mo, and shown to modulate the activities of mature neutrophilic granulocytes by Gasson et al., Science 226:1339 (1984). Cloning and expression of recombinant human GM-CSF from various sources has been reported by Cantrell et al., Proc. Natl. Acad. Sci. USA 82:6250 (1985); Wong et al., Science 228:810 (1985); and Lee et al., Proc. Natl. Acad. Sci. USA 82:4360 (1985). Cantrell et al. isolated human GM-CSF sequences from cDNA libraries prepared from the HUT-102 cell line. The isolated human sequences were shown to direct synthesis of a biologically active GM-CSF using a yeast expression system.
In view of its potential as a therapeutic agent for treating various cytopenias, and its apparent effect upon mature granulocytes and macrophages, there is interest in bovine GM-CSF (bGM-CSF) in veterinary medicine. Therapeutic compositions comprising biologically active recombinant bGM-CSF or active homologues could be employed to augment immune responsiveness to infectious pathogens, or to assist in reconstituting normal blood cell populations following viral infection or other conditions resulting in hematopoietic cell suppression.